1. Field of the Invention
Use of a carrier-supported transition metal phthalocyanine catalyst for the removal of organic compounds containing oxygen and/or nitrogen from exhaust gases.
The invention relates to the use of a carrier-supported catalyst on the basis of transition metal phthalocyanines for the oxidation treatment of exhaust gases which contain volatile organic compounds containing oxygen and/or nitrogen.
2. Background Information
It is known that a catalyst can be formed from industrial metal phthalocyanines and a carrier to remove nitrogen oxides, carbon monoxide and/or residual hydrocarbons from exhaust gases (German Laid Open Patent Application No. 35 22 637 and European Laid Open Patent Application No. 0 228 398). For this purpose, the metal phthalocyanines are treated with oxidizing gas mixtures, so that in a controlled partial decomposition of the stable complexes, assisted by the wide separation of the metal ions from one another, as a result of the structure of the complex, a highly irregular, stable and highly-active catalyst preparation is formed which differs greatly from the stoichiometric oxide and from the stoichiometric metal complex.
Several processes are disclosed for the prior fixing of the metal phthalocyanine on carriers for transformation into the active components. These include the saturation of the carrier with solutions and suspensions, the precipitation of carrier materials from metal phthalocyanine suspensions, with subsequent shaping and drying, the conversion of metal phthalocyanines into soluble derivates, to facilitate saturation, and the direct synthesis of the metal phthalocyanine from soluble preliminary stages on the carriers. If the metal phthalocyanines are to be deposited on an intermediate layer and not applied directly on the carrier, this intermediate layer can be applied before the application of the metal phthalocyanines, but also simultaneously with the application of the metal phthalocyanines in a single step.
German Laid Open Patent Application No. 35 22 637 discloses the use of metal phthalocyanines only for the catalytic conversion of NO, CO and residual hydrocarbons.
The purification of exhaust gases or waste gases is expensive, and the manufacture of the catalysts represents a significant proportion of the cost. The criteria for the beneficial, undesirable and acceptable residual levels are constantly becoming stricter, and are being extended to cover new substances. In many cases, these stricter requirements are being written into laws. For these reasons, a broadening of the scope of application of economical and effective catalysts of the prior art is desirable. One notable use of these catalysts includes the removal of all types of organic compounds containing oxygen and/or nitrogen in exhaust gases. Such a removal is already legally required to a great extent, and will doubtless become even so in the future. Even after the already widespread practice of recovering these substances by condensation and sorption, there is a residual content in the exhaust which must be reduced to acceptable levels by catalytic reoxidation at the lowest possible temperature.